Use xfs_fsr to Keep Your XFS Filesystem Optimal

WEBINAR:On-Demand

"You can use the xfs_bmap utility to see the extent map for a
file that is stored on an XFS filesystem. If you execute it with
the -v verbose mode you can see the mapping of file offsets to
blocks in the filesystem. In the case of the file shown below, I
was unlucky; the filesystem split the 300MB tarball file over two
extents."